Fat Banana (Auto)

Nope, it won't harm the seedling directly. There are indirect ways it could harm it, though. Powdery mildew could be more likely to pop up on it, which isn't that harmful to the plant, but pretty unsightly. Different molds could pop up that might effect growth of your plant. I'm not quite sure if high humidity can promote diseases, but now that I think about it, I'm going to have to research it later. But, for the most part, I'm pretty sure you're safe. You'll definitely want to get the humidity down by the time the plant starts vegging, though. I like to shoot for around 60% in my veg room. I hope this helps. Happy gardening!